We could win the war in Ukraine by agreeing to permanently keep Ukraine out of NATO which is a fait accompli anyway since the member nations have already said they’re not going to war with Russia over Ukraine.
That's a strange definition of "win". Thats like saying you could win a mugging by handing over your wallet after they hit you with a baseball bat.
It's not a strange definition of "win". Winning means not getting into unnecessary fights where national interest isn't involved (for the US and many EU neighbors of Ukraine; Ukraine itself too, considering that they can never match Russia militarily).
Yielding to terrorists sets bad precedent. Where does it stop?